Particle-in-Cell Simulations of Injection Locking for S-Band Oven Magnetron Using Ultralow Energy

A novel coaxial-line injection-locked magnetron structure for an S-band microwave oven has been proposed, and simulation analysis has been conducted. The magnetron is regarded as a highly efficient orthogonal-field oscillator, with an injection port directly opened on the wall of its resonant cavity. It is coupling a certain amount of power into the interaction space through a coaxial line. The injection power is set at 32 W. During the start-up phase of the magnetron, the electron flow undergoes pre-modulation due to the influence of the injected small signal. When the injection duration is 20 ns, the maximum locking range is 3 MHz. The magnetron’s output signal is successfully locked by the external injection signal. The new structure combined with the short-time injection method achieves an ultralow energy injection-locking effect. Compared with the 10-ms pulse time of the traditional magnetron, the locking energy of this method is only 0.02. When the injection power is set to 200 W, the locking range extends to 8 MHz. In the locked state, changing the initial phase of the injected signal does not affect the phase difference between the output signal and the injected signal. The phase difference remains almost unchanged at the same frequency. This provides the possibility of controlling the frequency and phase of multiple magnetron arrays through single-channel injection in the future. This injection method can meet the array application requirements of magnetrons for ovens.